Combined oil and gas range



July 12, 1949, R M. SHERMAN 2,476,067

COMBINED OIL AND GAS RANGE Filed Feb. 26, 1944 2 sneaks-sheet 1RaZsZanMMw 41 Min/ 9 MM R. M. SHERMAN 2,476,067

COMBINED OIL AND GAS RANGE 2 Sheets-Sheet 2 July 12, 1949,

Filed Feb. 2a, 1944 a r.lI||ll||||7 v 0 00000000000 0a o ooooooo r NOOOOOOOOOQO/ OO0O0OOO OO 4 0090000 000 DOOOOOOOCOO QQWODOOOOOOOOOOOODOOOODOOO OOOOOOWOODTuOOOOOOOOOOJOODO L Patented July 12, 1949UNITED STATES ?ATENT OFFICE COMBINED OIL AND GAS RANGE Rallston M.Sherman, Glastonburmfionn.

Application February 26, 194i, Serial No. 5245,0512

1 Claim. 1

My invention relates to ranges, particularly but not exclusively tothose having provision for performing cooking operations, such asbaking, by heat derived from either oil or gas or from bothsimultaneously.

Heretofcre the attempt to heat the oven of a range by simultaneouslyoperated gas and oil burners and secure satisfactory advantage of theadherent characteristics of each burner has proved unsuccessful. It hasbeen found, that when heating the oven of a range by an oil burner,uniform heating of the oven, and consequently best baking performance,is secured by causing the products of combustion of the, burner totravel over the top Wall of the oven, down one of its lateral walls, andacross its bottom wall, in contact therewith, and hence to the stack. Onthe other hand, it has been found that best results are secured byplacing the gas burner beneath the oven, that is to say, in the passagebelow the oven for the products of combustion from the oil burner if therange is designed to heat the even by an oil burner as well as by a gasburner. It however has been found that placing the gas burner in thispassage so seriously interferes with the draft tending to move theproducts of combustion of the oil burner through the passage, when thegas burner is in operation, that it is impossible satisfactorily tooperate both burners. simultaneously. The attempt to overcome thisdefect by increasing the draft causes the products of combustion fromthe gas burner to fail to rise through the portion of the passage incontact with the lateral wall of the oven, and consequently under suchconditions the gas burner will not tend to heat the oven uniformly.Further, the attempt to overcome this defect by placing the gas burnerwithin the oven chamber has, with burners as heretofore constructed,failed to secure proper heating of the oven, for although best resultswith the gas. burner within the oven chamber aresecured when it is atthe top of that chamber, at which position it is almost obligatory toplace it to keepthe gas fumes and combustion products away from thefood, it does not, when so placed, securea wholly satisfactory uniformheating of the oven chamber but results in a pronounced unsatisfactorysharply decreasing temperature gradient between the p and bottomportions of the chamber.

With a range constructed according to applicants invention, however, itis possible to operate the oil and gas burners simultaneously so that:the stove top may be heated to the desireddegree by the products ofcombustion "of the oil burner,

which latter also heat the oven, any further heat required for heatingthe oven being obtained by burning gasat theupper portion of the ovenchamber in an improved way that heats the oven chamber uniformly.Further, with such a range the oven may be heated exclusively by eitherthe oil burner or the improved gas burning instrumentality within theoven, this instrumentality also being highly suitable for broiling foodplaced in the oven. Thus this improved gas burning instrumentality notonly serves for highlysuccessiul broiling andbaking but permits theoil-burner to be operated simultaneously therewith Without interference.

The above and further objects of the invention will be best understoodfrom the followin description when read the light of theaccompanyingdrawings of an embodiment of the invention, the scope of which latterwill be more particularly pointed out in the appended claims.

In the drawings Fig. l is a horizontal section of a range according tothe invention on the line l-] of Fig. 2;

Fig. 2 is a vertical section on the line 2-2 of Fig. 1,illustratingperf-orma-nce of a baking operation in the oven Fig. 3illustrates a detail of the range according to Figs. 1 and 2;

Fig. 4 is a vertical section of the oven chamber, corresponding to Fig.2, illustrating performance of a broiling operation in the oven;

Fig. 5 is a plan on an enlarged scale, with parts in section and partsbroken away, of the gas burning l-nstrumen-tal-ity, and associatedparts, of the range according to Figs. 1 to 4 inelusive;

Fig. 6 is a side elevation, with parts in section and parts broken away,of the gas burning instrumen-ta'lity shown in Fig. 5'; and

7 is a section on the line l -iof Figs. 5 and 6.

Referring to the drawings, the range illustrated comprises. theconventional range casing i having a stove top 3, on which latterbroiling and frying operations, and the like, maybe performed. Withinthe casingare walls forming an oven chamber 5, one lateral wall 1 of theoven being sufficiently spaced. from the corresponding lateral wall ofthe casing to form a compartment 9 in which is placed one or morecombustion tube range oil burners 'll of common construction.

As shown, the top wall 13-, lateral wall It and bottom wall 11 of theoven are each spaced from the corresponding walls of-"the casing l toafford communicatingspacesbrpassages l9, 2| and 23 for removing theproducts of combustion of the oil burner from the compartment 9 anddischarging them through an opening 25 in communication with the stackconnection 21 carried by the back wall of the casing I. The hot walls ofthe combustion tubes of the oil burners, and the products of combustionin the compartment 9, serve to heat the adjacent wall of the oven, whilethe products of combustion passing through the space l9 serve to heatthe stove top and the top wall of the oven chamber, the products ofcombustion in the spaces 2| and 23 further serving to heat the adjacentwalls of the oven so that the latter, as viewed in Fig. 2, is in effectenveloped by hot gases serving to heat its interior uniformly.

As has hereinbefore been explained, according to the invention insteadof placing in the space 23 beneath the oven a gas burner for heating it,or placing such burner elsewhere in the passages for conducting productsof combustion from the oil burner to the stack, the gas for heating theoven is burned exclusively Within the oven chamber, a novel gas burninglnstrumentality which will heat the oven by radiant heat being employedfor this purpose as hereinafter explained.

I-Ieretofore, in the attempt to heat an oven by burning gas within theoven chamber, an inverted Bunsen-type burner has been employed. Suchburner, in effect, forms at the upper portion of the oven chamber asheet of flame facing the bottom of that chamber. As a result the burnerforms an intensely hot zone at the upper portion of the chamber, butbecause of the blue Bunsen flame being non-luminous fails to radiateheat downwardly. Further it has been found necessary with such a burnerto cause the flame to burn substantially out ofcontact with the body ofthe burner lest improper combustion cccur'and cause generation ofdangerous amounts of carbon monoxide gas, and in consequence the body ofthe burner remains relatively cool and, like the flame, fails to form asource of radiant heat of suflicient capacity to have any appreciableeffect in heating the bottom portion of the chamber. As a result, withsuch a burner the bottom portion of the oven chamber, it has been found,tends to be heated almost exclusively by convection currents of the airor other vapors in the chamber, which air because the burner is at thetop of the chamber does not readily circulate throughout the height ofthe chamber but tends to form a dead air space at its bottom portion, sothat the upper portions of the chamber are unsatisfactorily over-heatedand the lower portion unsatisfactorily under-heated.

As illustrated, the gas burning device according'to the presentinvention comprises a manifold 29 within the oven chamber at its upperportion for supplying gaseous fuel to a plurality of pipes 3|, whichpipes at their free ends are closed by caps 33. As shown, the manifoldand pipes are supported by bars 34 carried at their end portions by theopposite walls I and I of the oven, the pipes being received in notches35 formed in the upper edge portions of these bars. As shown, each pipeis provided on its under side with a row of spaced perforations 36 sothat gaseous fuel admitted to the pipe may discharge therefrom throughdownwardly facing openings provided by these perforations. For receivingthe gaseous fuel discharged through the perforations 36 is provided achamber 31 the walls of which, as shown, are formed of sheet' refractorymaterial such as stainless steel. As

- illustrated, the walls of this chamber comprise the downwardlyconverging side walls 39 which it will be observed face downwardly aswell as laterally so that when heated to incandescence, as hereinafterexplained, they will emit radiant heat downwardly as well as laterally.Also, as shown, the walls 39 are joined at the bottom of the chamber bya relatively narrow wall 4|, the top of the chamber being closed by thepipe 3|. As illustrated, the upper edge portions of the sheet formingthe walls 39 and 4| are curved to fit the upper portion of the pipe andat the top of the latter are welded to each other and to the pipe asindicated at 43. As shown, each of the opposite ends of the chamber isclosed by an imperforate' plate 45 welded at its edges to the pipe andto the side and bottom walls of the chamber. The sheet forming the walls39 and 4: of the chamber 31 conveniently is preperforated material, theperforations, indicated at 41, being of relatively small diameter andrelatively closely spaced so as to provide, on the exterior surfaces ofthe walls, openings each surrounded by a small increment of thosesurfaces of greater area than that of the opening.

The gaseous fuel supplied the pipes; 3| is distributed to the chambers31 by the rows of perforations 36 inthe pipes, which rows extend thefull lengths of said chambers so that substantially uniform amounts ofgaseous fuel will In operationv the amount of gaseous fuel supplied eachpipe 3| is such, in relation to the total area of the perforations 41 ofthe chamber 31 associated with that pipe, that only sufficient gas isdischarged through each perforation to form but a small button of flamein contact with that increment of the exterior surface of the walls ofthe chamber which surrounds the opening of the perforation on-thatsurface, as distinguished from the effect produced in the gas burnerheretofore attempted-"to be employed in ovens with which the gasdischarged burns out of contact with the body" of the burner. As aresult, in applicants device thewalls of the chamber having theperforations 41 are heated to incandescence, and the exterior surfacesofthose walls thus provide a source of radiant heat. I

The'gaseous fuel supplied the pipes 3| is mixed either with no air atall-or with insufficient air to support combustion of such fuel.Otherwise the fuel at the interior of the chamber would becomeignited,.with the result that the perforatedwalls of the chamber,particularly their exterior surfaces, would not be heated toincandescence." If no air is admixed with the gaseous fuel, combustionis supported wholly by air at the exterior of the perforations 41, thedistribution of the fuel afforded by these perforations being suchas toso reduce the amount of fuel discharged through each perforation that itburns with" a flame, of the general transparent blue remaining airnecessary to support combustion being secondary air at the exterior ofthe perforations; In the sense that the gaseous fuel discharging fromthe perforations, unlike thegaseous fuel discharged by a Bunsen burner,contains, as just explained, no air or insufiicient air to make it burnat all, making it necessary in each case to burn by secondary air thefuel discharged from the perforations, said gaseous fuel in the appendedclaims for convenience in terminology is called oxygen deficient" fuelor gas.

For admixing the gaseous fuel with an amount of air less than that whichwill support combustion or cause the fuel to ignite in the interior ofthe chamber 3?, in the present embodiment of the invention the manifoldinlet connection 49 is provided with a funnel-like head 51 carryinginteriorly thereof a nozzle 53 for discharging gaseous fuel into suchconnection axially thereof so as to draw exterior air through one ormore openings 55 in the immovable closure plate 51 of the head 5| foradmixture with the fuel discharged from the nozzle. As shown, the headis provided with a rotatable cap 59 provided with one or more openings 0I, each of which is adapted to be brought more or less into registrywith one of the openings 55 for adjusting the amount of air admitted,while the amount of gaseous fuel supplied the nozzle may be regulated bythe valve in the pipe 65 supplying such fuel to the nozzle. As shown,the manifold inlet connection 49 leads to the exterior of the oventhrough an opening G'l in the back wall of the oven, the walls of thisopening affording suflicient clearance about the connection to permit anamount of air necessary for combustion of the gaseous fuel to enter theoven whether the air admission openings 55 are open to cause primary airto be admixed with the fuel or are closed to cause the fuel to burnWholly with secondary air. As illustrated, the products of combustionfrom the gas burning device escape from the oven chamber through anopening 69 formed in its upper wall into the flue passage Hi and thenceto the stack.

As an example of the improved gas burning device above described, butwithout limitation thereto, each pipe 3| may be a length of standardinch so-called wrought iron pipe which is about 1.05 inches outsidediameter with a wall thickness of about 0.08 inch, the perforations 36in the pipe being 0.12 inch in diameter spaced on centers inch apart,while the chamber 31 may be about 7 inches long with its bot-tom aboutinch wide and 2 inches below the bottom of the pipe, the lateral andside walls of the chamber being made of a sheet of stainless steel about0.03 inch thick, consisting of 18% chromium, 8% nickel and 74% iron,which sheet has perforations 1? about 0.07 inch in diameter spaced oninch centers. By supplying sufficient amounts of ordinary city fuel gas,having a fuel value of about 550 B. t. u. per cubic foot, to cause thesmall button of blue flame at each perforation 47 to be of such diameterthat it contacts at its periphery with the buttons at the immediatelyadjacent perforations, the exterior surfaces of the perforated wall ofthe chamber will be heated to about 1600 F. in about 7 /2 minutes andthereafter maintained at that temperature. Compared to the maximumtemperatures secured, and the times required to secure them, with theinverted type of gas burner heretofore proposed, the temperaturessecured by applicants device are remarkably high and the times requiredto secure them remarkably short, for seldom do the temperatures securedwith said type of gas burner ever exceed 650 F. or require less thanabout 15 minutes to secure them.

The interior surfaces of the lateral walls of the oven chamber, andparticularly those of the walls 1 and 15, which walls preferably are ofrelatively thin low carbon steeel, say about 0.03 inch thick, arepreferably highly reflective as, for example, they may be brightchromium plated. This will cause the radiant heat emitted from theincandescent exterior surfaces of the side walls 39 of the gas burningdevice striking the lateral walls of the oven to be reflected downwardlyas, for example, rays emitted along paths ll will be reflected alongpaths 13 toward the bottom of the oven. Preferably, also, for the samepurpose the inner surface of the back wall of the oven and the innerexposed surface of the lining is of the oven door H are also highlyreflective. Above the gas burning device is shown a reflector plate 19preferably formed of metal having a polished chromium plated surface onits lower concave side for reflecting heat downwardly.

When the oven is arranged for baking, as shown in Fig. 2, there ispreferably employed for further diffusing the radiant heat throughoutthe oven a heat diffusing plate 55! positioned below the gas burningdevice, which plate may be formed with one or more openings 83. Asshown, the plate is carried by bars the ends of which are adapted to bereceived by the channel-shaped rack supports 8 carried by the walls 7and lb of the oven chamber, so that the diffusing plate may be removedand may be positioned at different elevations to suit baking conditions.As shown, the reflector plate 19 is similarly carried and supported bybars 89 so that the plate may be removed for cleaning purposes.

The exterior surfaces of the walls of the oven chamber preferably areunfinished, so as to provide dark relatively rough surfaces that willreadily absorb heat from the flue gases of the oil burner. Thereflective surfaces afforded by the interior surfaces of the ovenchamber act to prevent loss of heat through the oven walls from theinterior of the oven chamber when the gas burner is in operation. Thusthe oven surfaces are such as to facilitate absorption of heat from theflue gases from the oil burner, while at the same time effectivelyinsulating the oven from escape of heat through its walls when the gasburner is in operation. It will be understood that the interior of thetop wall of the oven also may afford a similar polished surface forinsulating purposes, and where the reflector plate 79 is not employedsuch surface will also act to reflect the radiant heat downwardly.

In Fig. 4 the oven is shown arranged for broiling. Under theseconditions the diffusing plate iii is removed, and a removable grid 91for supporting the food to be broiled and an associated drip pan 93 arepositioned below the bottom of the gas burning device on a removablerack 95 carried by the adjacent rack supports 81. The incandescentbottom walls 4! of the gas burning device, in conjunction with theincandescent lateral walls 39 thereof, and the action of the reflectorplate is form a superior source of broiling heat comparable to and infact superior to that of glowing charcoal.

As illustrated in Fig. 2, in the oven resting on its bottom is a thickplate 91 of substantially the transverse dimensions of the oven, thisplate being say about /2 inch thick and formed of cast iron or aluminumor other material having a high capacity for absorbing heat. Preferably,the surfaces of the plate are unpolished so that it will absorb radiantheat emitted from the gas burn-

